Our son wanted a science birthday party. There were science experiments and owl pellet dissections; but the biggest hit was the Kermit D. Frog Dissection birthday cake that my wife made.
Step 1: Bake the cake and mix up the Rice Crispy Treats
The cake is simply out-of-box cake mix - any flavor you like. She used Red Velvet just to keep the theme going. Two rounds with a little cutting creates the basic shape nicely. The arms, legs, tongue, and organs get fashioned out of the rice crispy treat mix. Everything is laid out to get the basic scale correct.